1. Field of the Invention
This invention relates to paper supply mechanisms of the type used with ink jet printers, facsimile machines, copiers and the like. More particularly it relates to a roll feed mechanism in which a supply of paper, or other sheet material, is stored within an imaging drum and is arranged to feed to the outer surface of the drum where writing or imaging operations occur.
2. Brief Description of the Prior Art
Countless arrangements have been used to supply paper and other sheet materials automatically to many different types of reproducing machines. In some of these, cut sheets are fed individually from a supply stack, but it is difficult to feed the sheets onto and from the imaging drum, and complex mechanisms are usually required to perform these operations. In other feed systems, paper is fed from a continuous roll into the reproducing equipment and is cut into individual sheets either before or after the imaging operation. In some instances, the continuous supply of paper is cut into individual sheets of the desired length before being fed onto the drum in an effort to overcome the problems associated with feeding a continuous supply onto the drum.
Various machines have been provided for storing a supply of web materials in a roll within a drum, withdrawing the material around the outside of the drum, where it is utilized for imaging or other purpose, and returning the web to a disposal roll within the drum. Such a machine is described for typewriter ribbon in U.S. Pat. No. 866,624 to Collier. Photocopier machines have used similar mechanisms to supply incremental replacement portions to the outside of a photocopier drum and then return the used material to a storage roll within the drum. Examples of such machines are shown in U.S. Pat. Nos.: 4,097,138 to Kingsley; 4,102,570 to Shimoda; 4,231,652 to Moser and Wegmann; and 4,239,375 to Eisbein and Wegmann. All of such machines are designed for relatively slow rotation of the imaging drum and for use in applications where web materials are used at a relatively slow rate. Because of the gradual and continual shifting of the center of gravity as the web is fed from the supply to the disposal roll, it is not possible to dynamically balance the drum for higher speed operation.
U.S. Pat. No. 3,829,208 to van Meljel discloses a copy machine in which a a supply of sensitized web material is stored on the axis of and within the drum and withdrawn around the outer surface of the drum. The web is utilized during the rotation of the drum to produce photocopies and when it is to be replaced by a fresh supply of web, the fresh web is drawn from within the drum and wrapped around the exterior while the used web is discarded away from the drum. The driving force for the web is provided by two pairs of rollers; a first pair carried by the drum, which engage the web only after it has passed around the exterior drum surface, and a second pair of rollers which are spaced from the drum and mounted in a fixed position relative to the rotation of the drum. Tensioning of the web is provided by a roller mounted within the drum which is spring biased against the web in the space between the supply roll and the exit slot in the drum. The forces introduced by the resistance to rotation of the supply roll and the friction of the web on the drum surface are exerted on the drive rollers which are engaged only after the web has passed around the drum. Such an arrangement has particular difficulties where it is important to store larger quantities of sheet material within the drum and when using sheet material, such as paper, that may have higher friction with the drum surface, or which is subject to distortion by stretching when excess tension is applied. The machine is intended only for use with web materials that are to be discarded.